docs: def add_object(self, nidm_object, export_file=True):
          """
          Add a NIDMObject to a NIDM-Results export.
          """
          if not export_file:
              export_dir = None
          else:
              export_dir = self.export_dir
  
          if not isinstance(nidm_object, NIDMFile):
              nidm_object.export(self.version, export_dir)
          else:
              nidm_object.export(self.version, export_dir, self.prepend_path)
          # ProvDocument: add object to the bundle
          if nidm_object.prov_type == PROV['Activity']:
              self.bundle.activity(nidm_object.id,
                                   other_attributes=nidm_object.attributes)
          elif nidm_object.prov_type == PROV['Entity']:
              self.bundle.entity(nidm_object.id,
                                 other_attributes=nidm_object.attributes)
          elif nidm_object.prov_type == PROV['Agent']:
              self.bundle.agent(nidm_object.id,
                                other_attributes=nidm_object.attributes)